1. Field of the Invention
The invention relates to a mower-conditioner conditioning roller, to a method of manufacturing such a roller and to a mower-conditioner equipped with such a roller.
Mower-conditioners comprise, in particular, a frame bearing a plant-cutting device and a device for conditioning the cut plants. This conditioning device is situated immediately after the cutting device. These mower-conditioners are hitched to the front or to the rear of agricultural tractors allowing to drive and move them.
The purpose of conditioning the forage is to reduce the length of time during which the harvest runs a risk of being damaged by rain. What conditioning actually allows is to reduce the overall drying time and to synchronize the stem and leaf drying.
Conditioning allows the protective film of plants to be broken open in order to increase the speed at which the plants dry and encourage uniform drying. Conditioning is highly effective when performed at the time of cutting.
The protective film is broken open by passing the plant between simple rollers or grooved rollers, the resulting squeezing bends or breaks open the strands of grass at intervals of 5-10 centimeters and may bruise the leaves. Thus, the purpose of conditioning is to process the forage to a certain extent in order to optimize drying, while at the same time limiting the degree of fragmentation and defoliation.
2. Discussion of the Background
Various roller-type conditioning systems exist, the main ones being:                roller conditioners where the rollers have a hard rubber covering, and        roller conditioners where the rollers have steel sections.        
Roller conditioners with rubber reliefs are known, for example, from patents FR 2 390 083 and U.S. Pat. No. 3,732,670. With this technique, the harvested products are conveyed into an inlet orifice formed between two conditioning rollers, these rollers having, on their exterior periphery, reliefs or protrusions lying a certain distance apart, the reliefs of one conditioning roller collaborating with depressions formed between the reliefs of the other conditioning roller.
Various relief designs have been developed to suit the plants that are to be conditioned, particularly for example for fragile plants such as clovers, alfalfas and, more generally, leguminous plants. In these devices, the intensity of the conditioning operation is also regulated by varying the pressure with which the rollers are pressed together.
These rubber roller conditioners consist of a cylindrical core to which the rubber covering is added. These rollers are very expensive to manufacture and have a fairly short life.
Conditioners comprising rollers with metal section pieces have been described, for example, in document U.S. Pat. No. 6,346,067. These conditioners have an improved service life but display several drawbacks particularly as a result of the difficulty experienced in producing satisfactory reliefs and in the industrial-scale manufacture of high-performance rollers at a reasonable cost.
Because of the difficulty there is in obtaining metal sections specially suited to this application, the effectiveness of the conditioning of plants of various kinds with such rollers is somewhat uncertain.
The high weight of the known rollers in mower-conditioners also presents a problem, especially as machines are becoming increasingly wide which means that more robust and therefore more expensive support means are required.